Previous attribution studies have quantified the effects of climate change on individual Atlantic storms: for example, researchers estimated that up to 38 percent of the extreme rainfall that Hurricane Harvey ejected in southeast Texas in August 2017 was due to climate change. . Dr. Reed was among the researchers who confirmed that climate change also played a role in Hurricane Florence in 2018 and Hurricane Dorian in 2019.
The new study is unusual in that it examines the effects of climate change not on a single hurricane, but on the entire hurricane season, including not only the storms that grab the headlines, but also the seemingly ordinary ones. Dr Reed said the findings provide convincing evidence that anthropogenic impact is not an anomaly limited to major events like Harvey.
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“If you just do it objectively throughout the season, you get similar results,” he said.
Rosimar Rios-Berios, a research meteorologist at the National Center for Atmospheric Research who was not involved in the new study, said a full-season study of hurricanes rather than individual storms provides a higher degree of confidence that the findings accurately reflect the role of climate change.
“There is a lot of power in studying individual events, but in the end one event is not enough because every hurricane is different,” she said.
A separate analysis released on Monday found that climate change is also likely to have increased the intensity of rainfall from two severe tropical storms that hit Southeast Africa earlier this year. But researchers said that due to a lack of high-quality meteorological data for the region, they could not measure the exact impact of global warming on these storms.
Dr Reed noted that the same methodology used by his team could be used to quantify the impact of climate change on near-real-time storms – or to illustrate how much worse storms would become if nations continue to burn fossil fuels.
The study, published on Tuesday, compares the hurricane season in 2020, as we experienced it, with the hypothetical hurricane season in 2020 in a world that has not been warmed by human activity. Since the 19th century, burning oil, gas and coal has increased average global temperatures by 1.1 degrees Celsius or 2 degrees Fahrenheit. It is also possible to compare the season, as experienced, with the version that may occur after, say, 1.5 or 2 degrees Celsius warming – the threshold above which scientists say that highly destructive storms become significantly more -probable.
“It’s important not to plan hurricane season in 2020 in the future,” Dr. Reed said. “This is to plan what the hurricane season in 2020 would look like, plus climate change in the future.
Raymond Jong contributed to the reporting.